1. Field of the Invention
The invention relates generally to a blasting calibration of a chill mold.
2. Description of Related Art
Among the related art are cooled ingot molds in which cooling channels are inserted into the tube walls, parallel to the longitudinal axis, which are able to have cooling means applied to them.
Furthermore chill tubes and also ingot molds are known which have vertical and/or horizontal channels in the mold walls into which temperature measuring elements can be inserted.
Because of the wear of a mold during casting, it is necessary to take it out of operation after a certain time in use, and to recalibrate it. For this purpose, each mold is first dechromed and then ground internally. Subsequently, a calibrating mandrel is placed into the mold, which in its external dimensions is equivalent to the internal dimensions of the new mold. After the insertion of the calibrating mandrel, the end faces of the mold are tightly closed, using plates.
Thereafter, the outer surface of the mold is covered with a suitable explosive, and this is detonated in a vessel filled with a fluid medium. Because of the blasting energy liberated, on the one side, and the counterpressure of the liquid medium on the other, the inner wall of the mold is pressed against the calibrating mandrel. In this manner, the mold gets back its exact inner contour required for its use in casting operation.
However, because of the wear of the mold during casting, and because of the internal grinding after deplating the chromium coat, it cannot be avoided in this method that material is removed, and as a result, the wall thickness of the mold is reduced during its repair, and consequently, the outer dimensions are reduced.
In order not to deform the bores in the mold in unacceptable fashion during the blasting calibration, no matter whether the bores are intended as cooling channels or receptacles for temperature measuring elements, filler pieces, preferably of high-grade steel, are inserted into the bores first, and are fitted exactly to the bores. Both the manufacture of these filler pieces and their mounting in the bores, as well as their dismounting, are connected with comparatively high time and manufacturing expenditure.
It is an object of the invention to provide a method for blasting calibrating molds, especially in the form of chill tubes and ingot molds, which is easier to control and relates to lower expenditure.
These and other objects of the invention are achieved by a method for the blasting calibration of a chill mold (1), especially in the form of a chill tube or an ingot mold. Bores (5), which are provided in the chill mold wall (2), are filled up. Thereafter, a calibrating mandrel is inserted into chill mold (1) and the outer surface (4) of the chill mold (1) is covered with an explosive material, whereupon the explosive material is ignited, and thereby the inner side (3) of the chill mold wall (2) is pressed against the calibrating mandrel. In accordance with the invention, the chill mold (1) is reinforced in its wall thickness, at least at its end regions, by building-up welding before the blasting calibration, then the bores (5) are filled up with a free-flowing material and tightly closed at the ends, whereupon the blasting calibration is carried out, and subsequently the end regions are processed to a new measure.